Electronic camera flashes have traditionally been based on arc lamps typically a xenon flash tube. However, such flash tubes are too bulky for today's ultra thin cell phones, smart phones, tablet computers and other ultra thin devices. A majority of smart phones now come equipped with a digital camera and increasingly many additionally include a flash unit to enable picture tacking in low light conditions. In such devices the flash unit comprises a white light emitting Light Emitting Diode (“white LED”). Typically white LEDs are based on LED chips that emit in the blue or ultraviolet part of the electromagnetic spectrum and include one or more photoluminescence materials (e.g., phosphor materials), which absorb a portion of the light emitted by the LED and through a process of photoluminescence re-emit light of a different color (wavelength). The LED chip generates blue light and the phosphor(s) re-emits, for example, yellow light or a combination of green and red light, green and yellow light, green and orange or yellow and red light. The portion of the blue light generated by the LED that is not absorbed by the phosphor material combined with the light emitted by the phosphor provides light which appears to the eye as being nearly white in color. Typically the phosphor material is mixed with a liquid light transmissive material, such as silicone or epoxy material, and the mixture applied to the light emitting surface of the LED chip. It is the phosphor material that gives rise to the characteristic yellow to orange appearance of the flash unit in an off-state. Whilst white LED based flash units are compact it is desirable if they were capable of generating a flash with a greater range. Embodiments of the invention, at least in part, address this problem.